A failure to find human remains that might account for an estimated 80 bodies thought to still be missing after the downing of MH17 has revived informed speculation in Canberra that a significant number of the victims might never be accounted for.

Australian officials in Kiev are reluctant to canvas such a grim prospect publicly. But in the absence of significant identifiable portions of the Malaysian Airways Boeing 777 aircraft having survived the crash, they are concluding that much of the fuselage was consumed in an inferno ignited at the point where the engines and wheel sections crashed to earth near the village of Grabovka on July 17.

"It's a reality we'll have to deal with sometime," Fairfax Media was told. "I hope we have accounted for a big number, but the fact is that the fuselage was consumed by fire . . . and you know what that can do to the human body."

Pro-Russian rebel Yuri near where searchers look for remains and possessions near the MH17 crash site. Photo: Kate Geraghty

Prime ministerial envoy Angus Houston has side-stepped questions on the body count a day after he confirmed that the Dutch-led search for body parts and passengers' belongings on a 50-square-kilometre apron around the villages of Grabovka and Rassypnoe was being postponed.

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Air Chief Marshal Houston argued that Canberra would await the conclusion of the DVI [disaster victim identification] process being conducted in the Netherlands on remains that had been flown out from Kharkiv, in Ukraine's northeast.

But Air Chief Marshal Houston defended a search effort that had been greatly compromised by intensified fighting in a roiling separatist war.

He conceded that an ambitious recovery plan he outlined in the days after the crash for "all the bodies, all the possessions and all the wreckage" had been pared to the bone, but he told Fairfax Media in a phone interview that "all the key decisions were very good".

He said: "Okay – we came up against all kinds of difficulty and obstruction, but in the main I'm confident that we recovered most of the remains.

"Basically, we have been right through the area . . . but it's a contested area.

''The initial plan was based on us getting full co-operation and us being able to secure the site, but this was never achieved so we adapted the plan in a way that allowed us to succeed to the best of our ability while keeping our people safe. We negotiated with the separatists [through the OSCE] but we were unable to achieve anything like the conditions necessary to achieve the plan as envisaged."

Despite speculation that neither side in the war was likely to countenance a return to the area by international search parties, Marshal Houston predicted that, in time, security would improve and with less vegetation after the harvesting of dense summer crops now quilting the area "we'll come back to make sure that no identifiable remains have been left behind".

Marshal Houston was intent on sending a series of seemingly contradictory signals – insecurity forced a paring back of the planned search; nonetheless it had been thorough; the body parts found had been small in size; permissiveness in the area had prevented the Australians from doing all that they wanted to do, but it was now accepted that the initial recovery by the rebels and Ukrainian emergency services had been ''a good job''.

The areas in which the Australian-Dutch investigative team had expected to find many body parts revealed only small remains, leaving the Australians surprised by the thoroughness of the initial Ukrainian recovery operation – "but we don't consider the search complete".

However, he insisted that this new understanding of the local reaction to the crash did not negate the need for the Australians and Dutch to have searched the site.

"We have removed many body parts and we had to make sure that we had as many as we could find. There was one area near the chicken farm [which became a base for the Australian-Dutch search in the immediate vicinity of Grabovka], which had not been previously searched, and we found a lot of remains there.

"It was vitally important for the families [of the dead] that we went in to do this work. There were numerous reports of human remains on the ground, so it was essential that we go in – but we didn't find any big body parts."

Mr Houston also shed light on the conduct of the search, which Australian Federal Police Commander Mark Harrison explained on Tuesday was targeting sections of the crash site selectively, rather than speculatively.

Asked about maps used by the searchers that were covered in yellow dots, Marshal Houston said the maps had been produced using satellite imagery of where the aircraft debris had scattered – the more yellow dots, the more concentrated the debris.

"The whole area was imaged with high-tech sensors, the latest technology which helps you to find things you might not find with a traditional search and a lot of this was produced by satellite.

"I don't want to discuss the detail, but those yellow dots were a part of the picture."

Apart from the human remains recovered – which he refused to quantify in terms of the number of victims they might represent – Mr Houston said that Australian possessions had been recovered from the site and the investigators had had access to a rail wagon at Torez, in which the rebels had been storing some of the victims' possessions to be handed over to the international team.

The searchers had had ''three or four good days'', but "there was extensive military activity on the approaches to the site and the separatists became quite jittery – we confronted more and more restrictions which became more and more of a hindrance.

"We got to a point at which they were building a defensive line . . . which meant that we could not achieve the mission we were attempting with unarmed people.

''It just wasn't going to work.

"Add to this that we had military activity going on around us – mortars, artillery."

Mr Houston revealed that the initial objective of gathering in as much of the wreckage as possible had become moot on the advice of international aviation crash experts who had concluded that attempting to reassemble the aircraft from the debris was not necessary because its fate had become quite clear – "it was cut and dried, everyone knew that it had been shot down, so there was no need to put it back together to establish what had happened".

At the same time, he said that there were sections of the wreckage that the investigators had wanted to examine, but this was not possible because of separatist restrictions on the investigators' movements.

"This was a reality we had to work with," he said. "We have photos and imagery, but not the actual pieces of the aircraft. But some there were some pieces that will be critical to the investigation that are now in the hands of investigators."